The present invention relates to a nebuliser device intended for an inhaler. The invention also relates to an inhaler apparatus equipped with such a nebuliser device.
Bronchial therapy normally uses inhaler apparatuses which permit the fine dispersion of a liquid or powdered active ingredient formulation and its controlled release into an air stream which is inhaled by the patient. To achieve optimum efficacy it is important that as large as possible a part of the particles (droplets) produced in this manner has a maximum size of 5μ.
Classic inhaler apparatuses more or less meeting these requirements use pneumatic nebulisers equipped with electrically powered compressors. Owing to the required compressors, power units or accumulators, these apparatuses are comparatively voluminous and heavy and are therefore only of limited suitability for mobile use.
Although inhaler apparatuses equipped with nebulisers based on ultra-sound are in general lighter and less voluminous, they are substantially less efficient. Tests have shown that only about 35% of the particles produced with such apparatuses have the required size of less than 5μ. Moreover, like the apparatuses equipped with pneumatic nebulisers they require electric energy and their mobile use is therefore relatively complicated, at least when used together with the components required for the electricity supply. The ultrasonic influence may furthermore also destroy the medicinal drug.
A nebuliser device of the generic type is known from document EP-A-0608176. This document discloses a pneumatically driven nebuliser device especially designed and meant for air purification applications, which device produces and releases into the ambient air a fine haze of active ingredient formulation by means of a fractionating cascade in-line with a nebuliser nozzle. The device is conceived for stationary use and is meant for continuous operation at an air through-put of 150–200 litres per hour. A relatively large amount of liquid active ingredient formulation gets caught in the fractioning cascade and has to flow back, which requires an essentially vertical operating position of the nebuliser. For the intermittent operation of a portable inhaler apparatus which in practice often lasts only for a few breaths, the nebuliser device designed for stationary continuous operation is at best of limited suitability also because of the limitation of the operating position.